Apnoeic oxygenation via nasal cannulae: 15 L min–1 versus high flow

Abstract

that the obese synthetic manikin was equivocally realistic, in that the landmarks were equally difficult to palpate and because it simulated bleeding.Our study demonstrates that this novel 'obese neck' synthetic model reproduces many of the difficulties encountered when performing an eFONA in an obese patient: it performed in a similar fashion to an obese meat-modified model and was more challenging than a traditional 'slim neck' manikin, while avoiding the practical hygiene issues associated with using pork belly to modify manikins. Such synthetic manikins may be useful tools for improving eFONA training in the future.

Apnoeic oxygenation in morbid obesity: a randomised controlled trial comparing facemask and high-flow nasal oxygen delivery

“…The only directly comparable study is in non-obese older patients which reported similar results. 17 Our findings align with previous studies which report that both flow rate 18 and proximity of fresh gas flow to the respiratory epithelium 19 influence apnoeic oxygenation efficiency.…”

“…Oxygen delivery characteristics may mitigate the risk of desaturation 18 and this study supports this notion. However, the unexpectedly high proportion of patients in the FM group reaching 18 min without desaturation and the wide variability in P a o 2 during apnoea in both groups also suggests that oxygen delivery characteristics are not the primary determinant of whether patients desaturate during apnoea.…”

“…In these cases the apnoea time was less than 5 min, comparable with time to desaturation in obese patients who were not given supplemental oxygen during apnoea. 14,34 This pattern, an apparent dichotomy between patients who do and do not 'tolerate' apnoea, was reported as early as 1973 35 and has been replicated in studies in both obese 14,18 and non-obese patients. 17 Clinically, this is an important finding: the implication is that for some patients e whatever the delivery method e supplying oxygen does not greatly increase the duration of apnoea without desaturation.…”

“…This was also a limitation of other studies performed around the same time as ours, which also used longer apnoea periods. 18,20,32 Time to desaturation as an outcome is therefore sensitive to study design and it does not describe the risk of desaturation during apnoea. In retrospect it is clear that desaturation risk, as used by a recent study in high-risk patients undergoing endoscopy, 33 would have been a better primary outcome.…”

Facemask or high‐flow nasal oxygenation: time to switch?

“…Oxygen flow rate at various locations during apnoea has also been investigated. Modelling, simulation and clinical data have all demonstrated that as flow rates increase, so too does apnoea time [8, 15–16].…”